Residents of the embattled Yemeni capital of Sana’a braced for a redoubling of air strikes following the killing Monday of the country’s former dictator Ali Abdullah Saleh and the apparent unraveling of a Saudi plot to depose the regime headed by the Houthi Ansarullah movement.

Saleh, 75, had ruled Yemen as a US-backed dictator for 30 years until being forced out by a popular uprising in 2011-2012. He was shot and killed by Houthi militiamen while fleeing heavy fighting in the capital between the Houthis and his own loyalists.

The two sides had maintained a tenuous alliance since 2014, when the Houthi rebel movement—which has its roots in the Zadi branch of Shia Islam to which Saleh himself belonged—swept down from the north and took control of Sana’a. Already in an advanced state of disintegration, that alliance broke down definitively over the past week, with armed clashes between the Houthis and Saleh’s loyalists that left over 125 dead.

On Saturday, Saleh made a televised speech renouncing his alliance with the Houthis and calling for the army and police to reject any orders coming from their regime. He also called for a dialogue with the Saudi-led “coalition,” which—with substantial logistical support and weapons provided by Washington—has been waging a near genocidal war against the Yemeni people for the past 33 months.

The Houthis charged Saleh with attempting a Saudi-backed coup. This assessment was substantiated in an analysis published by Al Jazeera based on interviews given by Yemeni officials on condition of anonymity.

These officials confirmed that Saleh’s break with the Houthis had been planned in Abu Dhabi earlier this year in consultation with top officials of Saudi Arabia and the United Arab Emirates, the oil-rich Gulf sheikdom that has played a major role in the assault on Yemen.

The plan, according to these officials, called for switching Saudi backing from Abd-Rabbu Mansour Hadi—Saleh’s former vice president who was installed following the mass upheavals of 2011-2012 and subsequently forced out by the Houthi rebels—to a regime led by Saleh or one of his sons.

Hadi, who lives in exile and under apparent house arrest in Saudi Arabia, had already lost the support of the UAE, which shifted its backing to the southern secessionist movement led by Aydarous al-Zubaidi, leading to armed clashes between UAE-backed forces and elements loyal to Hadi.

For decades, Saleh had served as both Washington’s and Riyadh’s man in Yemen. A former military officer, he first came to power in 1978 as the ruler of the US-backed North Yemen, at a time when a Soviet-backed People’s Democratic Republic of Yemen ruled in the south. When the country was unified in 1990, in the midst of the Stalinist dissolution of the USSR, Saleh assumed the presidency over all of Yemen.

With the Cold War over, Saleh maintained Washington’s backing, portraying himself as the sole figure capable of holding the fractious country together, balancing off opposing factions, including the Houthis in the north, separatists in the south and Sunni Salafist forces. Subsequently he secured massive US military support in the name of the global war on terror. In the process, he is believed to have a amassed a personal fortune in the tens of billions of dollars. The Obama administration supported Saleh until the bitter end as his troops opened fire on mass demonstrations, killing and wounding hundreds.

Following Saleh’s ouster in 2012, both Riyadh and Washington have upheld Hadi as the leader of the sole legitimate government of Yemen. In reality, he was brought to power as part of a “transition” deal concocted by the US and the Saudi monarchy to quell the mass popular uprising in Yemen, while granting Saleh immunity and maintaining the bulk of his regime intact. Hadi was subsequently installed as president through a one-candidate election in 2012. His two-year term expired over three years ago.

Both Washington and Riyadh are fighting to maintain a puppet government firmly under their control in Yemen, a country that shares a 1,100-mile border with Saudi Arabia to the north and a coastline on the Bab-el-Mandeb Strait, This narrow waterway linking the Red Sea to the Gulf of Aden and the Indian Ocean is a key strategic channel for global oil and natural gas exports.

Both the US and its Saudi ally are also determined to prevent the consolidation of a regime that is aligned with Iran, which has given limited support to the Houthis. US support for the Saudi aggression against Yemen is bound up with preparations for war with Iran, which Washington sees as a principal obstacle to its assertion of hegemony over the energy-rich Middle East.

To that end, the Saudis, with the support of the Pentagon, are expected to inflict even greater bloodshed upon the population of Sana’a in the coming days. The Saudi military issued a warning to residents of the Yemeni capital on Monday. “We ask civilians to remain at least 500 metres (yards) away from Houthi military vehicles and gatherings,” it said. Outside of a complete evacuation of Sana’a, complying with such a directive is impossible. It merely sets the stage for a further mass slaughter in a war that has already killed at least 12,000 civilians.

The escalation of Saudi airstrikes combined with the street fighting provoked by Saleh, with the backing of the Saudis and the UAE, has further deepened what is universally recognized as the worst humanitarian crisis on the face of the planet.

The United Nations issued a statement Monday calling for a “humanitarian pause” in the fighting. “The escalating situation threatens to push the barely functioning basic services ... to a standstill,” it said. “These services have already been compromised with the latest shock of the impact of the blockade,” it added, referring to the Saudi regime’s blocking of Yemeni airports, sea ports and land borders and turning back food, medicine and other relief supplies.

“Ambulances and medical teams cannot access the injured, and people cannot go outside to buy food and other necessities,” the statement continued. “Aid workers are unable to travel and implement critical life-saving programs at a time when millions of Yemenis rely on assistance to survive.”

The Saudi monarchy, with US support, is now preparing to exact revenge for the failure of its plot to reinstall Saleh, including through measures that can lead to the deaths of millions of Yemenis from starvation and the further intensification of the worst cholera epidemic in modern history.